Réaliser un mini client Twitter [Tutoriel Windows n°2]

using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Animation;
using System.Windows.Shapes;
using Microsoft.Phone.Controls;
using System.Xml.Linq;
 
namespace MiniTwitter
{
    public partial class MainPage : PhoneApplicationPage
    {
        public MainPage()
        {
            InitializeComponent();
 
            SupportedOrientations = SupportedPageOrientation.Portrait | SupportedPageOrientation.Landscape;
        }
 
        private void button1_Click(object sender, RoutedEventArgs e)
        {
            WebClient twitter = new WebClient();
 
            twitter.DownloadStringCompleted += new DownloadStringCompletedEventHandler(twitter_DownloadStringCompleted);
            twitter.DownloadStringAsync(new Uri("http://api.twitter.com/1/statuses/user_timeline.xml?screen_name=" + textBox1.Text));
        }
 
        void twitter_DownloadStringCompleted(object sender, DownloadStringCompletedEventArgs e)
        {
            if (e.Error != null)
                return;
 
            XElement xmlTweets = XElement.Parse(e.Result);
 
            listBox1.ItemsSource = from tweet in xmlTweets.Descendants("status")
                                   select new TwitterItem
                                   {
                                       ImageSource =
                                         tweet.Element("user").Element("profile_image_url").Value.ToString(),
                                       Message =
                                         tweet.Element("text").Value.ToString(),
                                       UserName =
                                         tweet.Element("user").Element("screen_name").Value.ToString()
                                   };
        }
    }
}

<phoneNavigation:PhoneApplicationPage 
    x:Class="TMiniTwitter.MainPage"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:phoneNavigation="clr-namespace:Microsoft.Phone.Controls;assembly=Microsoft.Phone.Controls.Navigation"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    mc:Ignorable="d" d:DesignWidth="480" d:DesignHeight="800"
    FontFamily="{StaticResource PhoneFontFamilyNormal}"
    FontSize="{StaticResource PhoneFontSizeNormal}"
    Foreground="{StaticResource PhoneForegroundBrush}">
 
    <Grid x:Name="LayoutRoot" Background="{StaticResource PhoneBackgroundBrush}">
        <Grid.RowDefinitions>
            <RowDefinition Height="Auto"/>
            <RowDefinition Height="*"/>
        </Grid.RowDefinitions>
 
        <!--TitleGrid is the name of the application and page title-->
        <Grid x:Name="TitleGrid" Grid.Row="0">
            <TextBlock Text="http://www.tutomobile.fr" x:Name="textBlockPageTitle" Style="{StaticResource PhoneTextPageTitle1Style}" Margin="20,20,0,0" />
            <TextBlock Text="Twitter" x:Name="textBlockListTitle" Style="{StaticResource PhoneTextPageTitle2Style}" Margin="20,43,0,0" />
        </Grid>
 
        <!--ContentGrid is empty. Place new content here-->
        <Grid x:Name="ContentGrid" Grid.Row="1">
            <Button Content="Voir les tweets !" Height="70" HorizontalAlignment="Left" Margin="258,0,0,0" Name="button1" VerticalAlignment="Top" Width="216" Click="button1_Click" />
            <TextBox Height="32" HorizontalAlignment="Left" Margin="6,0,0,0" Name="textBox1" Text="" VerticalAlignment="Top" Width="263" />
            <ListBox Height="568" HorizontalAlignment="Left" Margin="0,78,0,0" Name="listBox1" VerticalAlignment="Top" Width="480" >
                <ListBox.ItemTemplate>
                    <DataTemplate>
                        <StackPanel Orientation="Horizontal" Height="150">
                            <Image Source="{Binding ImageSource}" Height="75" 
                   VerticalAlignment="Top" Margin="0,0,5,0"/>
                            <StackPanel Width="370">
                                <TextBlock Text="{Binding UserName}" Foreground="Yellow" FontSize="26" />
                                <TextBlock Text="{Binding Message}" TextWrapping="Wrap" FontSize="22" />
                            </StackPanel>
                        </StackPanel>
                    </DataTemplate>
                </ListBox.ItemTemplate>
            </ListBox>
        </Grid>
    </Grid>
 
</phoneNavigation:PhoneApplicationPage>

using System;
using System.Net;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Documents;
using System.Windows.Ink;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Animation;
using System.Windows.Shapes;
 
namespace MiniTwitter
{
    public class TwitterItem
    {
        public string UserName { get; set; }
        public string Message { get; set; }
        public string ImageSource { get; set; }
 
    }
 
}